The present invention relates to an engine system and engine control method, in which a catalyst can be warmed up fast after the start of an engine when the engine and the cataylst is still in a cold state.
Harmful components in exhaust gas of an internal combustion engine cause the problem of air pollution. Therefore, a catalyst converter is generally used in the internal combustion engine, which converts the harmful materials to harmless materials.
The catalyst converter does not work sufficiently when the temperature of the catalyst does not reach the predetermined temperature. Therefore, the harmful components are not processed and emitted as they are, when the catalyst is in a cold state (for example, just after the start of an engine). In order to solve such the problem, various methods of warming up fast the catalyst have been proposed in the prior art.
For example, Japanese Patent Application Laid-Open No. 61-205376 and Japanese Patent Application Laid-Open No. 6-213125 disclose a method of activating fast a catalyst due to increased temperature of exhaust gas, in which the amount of correction of retard of an ignition timing is increased according to the temperature of the engine in a cold state, that is, the increasement state of the temperature of a coolant, or the elapsed time after the start of the engine.
It is, however, difficult to warm up the catalyst with giving a comfortable feeling of acceleration in the prior art, because the ignition timing is retarded due to indirect informations such as the temperature of the coolant of the engine, etc.